In digital pathology, pathologists often have a need to draw very detailed polygonal regions or borders around areas of interest in magnified digital images in order to annotate the image. One single annotation can take over 30 minutes to draw.
Typically, the task of drawing the polygon consists of using a mouse continuously to trace a path around the area of interest. In particular, existing polygonal annotation tools have a fixed image on the screen while the mouse cursor is the point of drawing. The user moves the mouse around the image and it leaves a trail of vertexes from which the polygon is formed. The problems with this approach are several:
a. The users hands can get tired from doing this for prolonged periods without letting go of the mouse button.
b. The users may need to zoom in and out of the image while drawing the annotation so as to get a higher level of detail. This requires stopping the drawing function. Other technology sometimes allows the user to zoom in and out while drawing, but it causes the mouse cursor to move and draws a jagged edge on the polygon.
c. Users may make a mistake and wish to erase part of what they have drawn without having to start over on this very large complex polygon. Some viewers allow the user to make modifications to the polygon by manipulating the vertices afterwards, but this is very cumbersome.
d. The context around where the user is drawing while drawing is very important to the tasks. If an image is fixed on the screen, some parts of the image the user is drawing will be closer to the edge while they are drawing and therefore giving less context at that region the user is concentrating on.